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Date: Fri, 03 Apr 2015 18:10:44 -0700 From: Eric Dumazet <eric.dumazet@...il.com> To: Alexei Potashnik <alexei@...estorage.com> Cc: Joern Engel <joern@...estorage.com>, "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org Subject: Re: neigh use-after-free On Fri, 2015-04-03 at 17:57 -0700, Alexei Potashnik wrote: > > My understanding of the state when issue occurs is: > - neigh_destroy() has finished executing > - no timer for this neigh entry is pending or running > (which makes neigh_timer_handler behavior irrelevant) > - but kfree_rcu callback for the neigh entry has not executed yet > - at this point IP code finds the entry with __ipv4_neigh_lookup_noref > and starts operating on it. > Right. So far no rule here seems to be violated. As long as IP code finds a neighbor, it is allowed to use it. Freeing of the neighbor should not happen before rcu grace period. Problem is __neigh_event_send() is ignoring n->dead -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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